Which spoken languages (humanLanguage) are identified in Diffbot APIs?

Diffbot Automatic APIs identify and return the humanLanguage (spoken language) of most analyzed pages. This is returned as a two-letter ISO-639 code, with the exception of Simplified Chinese (zh-cn) and Taiwanese Mandarin (zh-tw).

(In the Article API, Diffbot-generated tags will be returned in the native language for pages in English, Chinese, French, German, Spanish, Japanese or Russian.)